An HHO kit is basically a kit that breaks down water to its basic components Hydrogen (highly flammable) and Oxygen and you basically turn the car into a water powered car you still need gas to get the engine started

Yea me and my dad and a couple of my cousins are working on one to install on our cars we have our test model on our Geo Metro and the gas mileage has gone up about 28% its a start but we want to perfect it but that takes time and money...which we are all short of XD